A quick explanation:
“site:.eu” – searches for sites that have European (.eu) TLD (top level domains)
“”use our awesome search tool to find the right candidates”” – pay attention to the quotes – searches for sites that have this exact string in their pages.
So “somebody” is looking for European websites that provide candidates.

Of course, it might also be a signature of an exploitable script. Or just a WordPress Premium Theme (with a security hole?) – as in the one located here: http://alexgurghis.com/themes/wpjobus/resumes/. Keep your eyes open – you can never be too careful about the plugins/themes you use on your website(s).